1. Field of the Invention
The present invention relates to an abrasive composition for the manufacture of tools for the execution of treatments of surfaces in the field of the stone materials and the ceramics.
The invention also relates to an abrasive tool manufactured by using the above-mentioned composition.
2. Background art
Various kinds of abrasive tools are known which have different structure as a function of the kind of use they are destined to: surface treatment, cut, perforation and the like. In the field of surface treatments the most common operations are roughing, smoothing, polishing, super finishing and the tools aimed at these operations generally assume the form of a grinding wheel or of tablets, sectors, inserts and other forms which are applied to suitable support plates or pads equipped with coupling means for the connection to a machine by means of which the treatment is carried out, or they are directly connected to the machine in any other known way. Among the abrasive materials those belonging to the family of the aluminum oxides, such as corundum, are commonly used, the silica based compounds such as silicon carbide, as well as the so-called xe2x80x9csuperabrasivesxe2x80x9d, that is natural or synthetic diamond powder and the synthetic nitrides, for example CBN (cubic boron nitride), essentially used in the field of the treatments of metal surfaces.
Up to now, for the treatment of the surfaces of stone-like materials, such as marble, granite and stones in general, or of ceramic materials, such as ceramics, gres and derivatives, abrasive compositions have been used which comprise an abrasive material, for example diamondiferous material or silicon carbide, agglomerated with a mineral binder, in particular a magnesian binder possibly with the addition of a phenolic resin, or with resinous binder generally consisting of epoxy or phenolic resins.
The abrasive tools using resinous materials as a binder present several advantages with respect to those using magnesian materials, the most important of which is the greater effectiveness of use, that is the greater speed of performing the treatment on surfaces of the same characteristics. They present, on the other hand, a lower support stiffness of the abrasive particles, what involves the tendency to produce an increased abrasion on tender materials, and hence they proved to be unsuitable with materials such as granite as regards the xe2x80x9cpore closurexe2x80x9d, i.e. the porosity reduction, of the surfaces under treatment. Besides, because of the relative elasticity of the resinous binder, beyond certain operating pressures the abrasive sinks into the binding matrix instead of attacking the surface to be treated, therefore, for example, ceramic surfaces cannot be treated when already installed. At last, each surface treatment among those mentioned above, requires various passages with abrasive tools of different grain size characteristics, therefore the treatment times are always relatively long.
The main purpose of the present invention is to provide a new abrasive composition for the manufacture of tools destined to the execution of surface treatments such as roughing, smoothing and polishing on stone materials and ceramics able to offer higher performances with respect to the current state of the art, both as the treatment life and the treatment execution time are concerned.
A particular purpose of the present invention is to provide an abrasive composition of the above mentioned kind which makes possible the manufacture of abrasive tools, whose compactness and stiffness can be optimized as a function of the use conditions, the kind of machine, the operating pressures, the number of revolutions and other operating parameters.
A further purpose of the present invention is to provide an abrasive tool for the treatment of surfaces of stone materials and ceramic materials characterized by an effectiveness of use considerably higher than that of the conventional tools.
These purposes are reached with the abrasive composition according to the present invention, comprising at least a superabrasive and a binder and characterized in that the binder comprises a frit approximately melting between 450xc2x0 C. and 650xc2x0 C. and a refractory material, said composition further comprising a chemically inert abrasive material for thermally and mechanically protecting said superabrasive.